Poka-yoke mounting system for an exhaust treatment device

ABSTRACT

An exhaust treatment system includes first and second exhaust conduits positioned on opposite ends of an exhaust treatment device. The exhaust treatment device includes a housing having a first outer diameter at a first end and a different second outer diameter at a second end. A clamp includes an inner surface engaging both the first exhaust conduit and the exhaust treatment device when the exhaust treatment device is positioned with its first end adjacent to the first exhaust conduit. The inner surface of the clamp is spaced apart from one of the housing and the exhaust treatment device when the second end of the exhaust treatment device is adjacent the first exhaust conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/058,342, filed on Oct. 21, 2013, which is a divisional of U.S. patentapplication Ser. No. 13/039,559 filed on Mar. 3, 2011. The entiredisclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure generally relates to a system for treatingexhaust gases. More particularly, a system for interconnecting andsupporting various exhaust treatment devices is described.

BACKGROUND

To reduce the quantity of NO_(x) and particulate matter emitted to theatmosphere during internal combustion engine operation, a number ofexhaust aftertreatment devices have been developed. A need for exhaustaftertreatment systems particularly arises when diesel combustionprocesses are implemented. Typical aftertreatment systems for dieselengine exhaust may include one or more of a diesel particulate filter(DPF), a selective catalytic reduction (SCR) system, a hydrocarbon (HC)injector, and a diesel oxidation catalyst (DOC).

During engine operation, the DPF traps soot emitted by the engine andreduces the emission of particulate matter (PM). Over time, the DPFbecomes loaded and begins to clog. Periodically, regeneration oroxidation of the trapped soot in the DPF is required for properoperation. To regenerate the DPF, relatively high exhaust temperaturesin combination with an ample amount of oxygen in the exhaust stream areneeded to oxidize the soot trapped in the filter.

The DOC is typically used to generate heat useful for regenerating thesoot loaded DPF. When hydrocarbons (HC) are sprayed over the DOC at orabove a specific light-off temperature, the HC will oxidize. Thisreaction is highly exothermic and the exhaust gases are heated duringlight-off. The heated exhaust gases are used to regenerate the DPF.

Over time, however, the DPF may degrade and become less effective.Replacement of the DPF or another exhaust treatment device may benecessary. Alternatively, the exhaust treatment device may be servicedor otherwise rejuvenated when the exhaust treatment device is removedfrom the system.

DPFs, DOCs and the like have been coupled to relatively smalldisplacement internal combustion engines for automotive use. It may alsobe desirable to treat the exhaust emitted from engines in otherapplications including diesel locomotives, stationary power plants andmarine vessels. These systems may be equipped with relatively largediesel compression engines. The exhaust mass flow rate from the largerengines may be more than ten times the maximum flow rate typicallyprovided. The size and weight of the exhaust treatment devices requiredfor large engines may make the components unwieldy and very costly.Therefore, a need may exist in the art for an arrangement to easilyservice and support the devices for treating the exhaust output from alarge diesel engine. Some of the exhaust treatment devices such as DPFsare relatively fragile and susceptible to fracture. Care should be takenduring DPF replacement and operation to avoid impact loading.Furthermore, it may be desirable to maintain a predetermined exhaustflow direction through the exhaust treatment device and also apredetermined rotational alignment between exhaust treatment devices.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

An exhaust treatment system includes an emissions treatment devicehaving an upstream end and a downstream end for treating exhaust emittedfrom an internal combustion engine. The exhaust treatment systemincludes a frame adapted to support first and second portions of theexhaust treatment system. The first and second portions of the systemare spaced apart from one another. The emissions treatment deviceinterconnects the first and second portions and is in receipt of exhaustfrom the first portion and provides treated exhaust to the secondportion. A first bracket is fixed to the frame and includes one of aprotrusion and a receptacle. A second bracket is adapted to be fixed tothe emissions treatment device and includes the other of the protrusionand the receptacle. The protrusion is positioned within the receptaclewhen the emissions treatment device is properly positioned. Theprotrusion interferes with one of the second bracket and the emissionstreatment device to preclude assembly when the emissions treatmentdevice is improperly positioned.

An exhaust treatment system includes first, second and third emissionstreatment devices positioned in series fluid communication with oneanother. The second emissions treatment device is removable from betweenthe first and third emissions treatment devices. A first bracket iscoupled to one of the first and third emissions treatment devices andincludes one of a protrusion and a receptacle. A second bracket is fixedto the second emissions treatment device and includes the other of theprotrusion and the receptacle. The protrusion is positioned within thereceptacle when the second emissions treatment device is properlypositioned. The protrusion interferes with one of the first bracket andthe second emissions treatment device to preclude assembly when thesecond emissions treatment device is improperly positioned.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic depicting an exhaust aftertreatment systemincluding a poka-yoke mounting arrangement;

FIG. 2 is a perspective view of a portion of the exhaust aftertreatmentsystem;

FIG. 3 is another perspective view of the poka-yoke system;

FIG. 4 is a side view of the poka-yoke mounting system;

FIG. 5 is a schematic of an alternate poka-yoke system having exhausttreatment devices properly assembled; and

FIG. 6 is a schematic depicting the alternate poka-yoke systemrestricting improper installation of an exhaust treatment device.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

FIG. 1 depicts an exemplary diesel exhaust gas aftertreatment system 10for treating the exhaust from a diesel compression engine 16. Theexhaust may contain oxides of nitrogen (NO_(x)) such as nitric oxide(NO) and nitrogen dioxide (NO₂) among others, particular matter (PM),hydrocarbons, carbon monoxide (CO), and other combustion byproducts.

Aftertreatment system 10 includes multiple exhaust treatment devices,such as a diesel oxidation catalyst 18, connected downstream from engine16 to receive the exhaust therefrom, a diesel particulate filter (DPF)20 connected downstream from DOC 18, and a NO_(x) reducing device 22,such as a selective catalytic reduction catalyst (SCR) or a lean NO_(x)trap connected downstream from the DPF 20 to receive the exhausttherefrom.

A regeneration unit 24 may be positioned upstream of DOC 18 to increasethe temperature of the engine exhaust and enhance the conversionefficiency of the NO_(x) reducing device 22. Regeneration unit 24 raisesthe temperature of the exhaust entering diesel oxidation catalyst 18 toapproximately 285° C. or greater to allow active HC dosing for activeregeneration of DPF 20.

Regeneration unit 24 includes an injector 26 for injecting a suitablereductant. Reductants may include urea, hydrogen or a hydrocarbon. Acontrol system, shown schematically at 28 in FIG. 1, is provided tomonitor and control injector 26. Control system 28 may include suitableprocessor(s), sensors, flow control valves, electric coils, etc. tocontrol injector 26.

As shown in FIGS. 2-4, DOC 18 and DPF 20 are interconnected by a firstband clamp 40. In similar fashion, DPF 20 and SCR 22 are coupled to oneanother with a second band clamp 42. A first flange 46 is fixed to afirst end 48 of DOC 18 by a suitable process such as welding. A secondend 50 of DOC 18 is fixed to a first end 52 of DPF 20 by first bandclamp 40. A second end 54 of DPF 20 is fixed to a first end 56 of SCR 22by second band clamp 42. A second flange 58 is fixed to a second end 60of SCR 22. First flange 46 and second flange 58 are fixed to a frame ofthe vehicle to support and mount exhaust gas aftertreatment system 10 ata desired location.

It should be appreciated that first flange 46 and second flange 58 arenot directly fixed to DPF 20. As such, vibrations and/or impact loadingthat may be applied to the vehicle frame will not be directly applied toDPF 20. First band clamp 40 and second band clamp 42 each include anelastomeric material 62 acting as a damper between DOC 18 and DPF 20, aswell as between DPF 20 and SCR 22.

As previously discussed, it may be desirable to easily remove DPF 20from aftertreatment system 10 and accurately reinstall the DPF aftercleaning or replacement. A poka-yoke system 70 includes a first bracketassembly 72 coupled to a second bracket assembly 74 by a removablefastener 76. A first end of bracket assembly 72 includes a flange 78fixed to a first bar 80. Flange 78 is fixed to first flange 46. Secondbracket assembly 74 includes a flange 82 fixed to a second bar 84.Flange 82 is coupled to second flange 58 via threaded fasteners (notshown). As noted, the opposite ends of bracket assemblies 72, 74 areinterconnected to one another with fastener 76.

Poka-yoke system 70 also includes a protrusion or first blade 86 fixedto first bar 80 that radially extends substantially parallel to andaxially offset from flange 78. A poka-yoke bracket 88 is fixed to anouter surface 89 of DPF 20 via a process such as spot welding. Poka-yokebracket 88 is arcuately shaped and includes a receptacle orcircumferentially extending slot 90 in receipt of first blade 86. Theoverall length or circumferential extent of slot 90 corresponds to thetolerance afforded to rotational alignment between DPF 20, DOC 18 andSCR 22. Rotational alignment or “clocking” of the exhaust treatmentdevices may be important because one or more of the treatment devicesmay include sensors that must be aligned with one another within acertain tolerance to properly function.

A second blade 96 is fixed to first bar 80. Second blade 96 includes aninner curved surface 98 defining its radially inward extent. Secondblade 96 extends radially inwardly a lesser distance than first blade86. A poka-yoke ring 100 is fixed to DPF 20 at a location axially spacedapart from poka-yoke bracket 88. In the example shown, poka-yoke ring100 may include a simple band clamp defined by a spring ring 102 havingends drawn together by a fastener 104.

Second blade 96 is axially offset from first end 52 of DPF 20 a distancesubstantially similar to the distance first blade 86 is axially offsetfrom second end 54 of DPF 20. By positioning the components in themanner described, a technician attempting to install DPF 20 in reversewill be precluded from doing so because first blade 86 will interferewith poka-yoke ring 100 due to the fact that no slot exists withinpoka-yoke ring 100. Reversing the exhaust flow direction through the DPFmay be detrimental to the operation of exhaust aftertreatment system 10.

Additionally, relative rotational misalignment will be prevented becausefirst blade 86 would interfere with an outer surface 108 of poka-yokebracket 88 if first blade 86 were not properly aligned with slot 90.FIG. 2 depicts a male radially extending element as first blade 86 witha female receiving element being slot 90. It is contemplated that therelative positioning of the male and female members may be reversedwithout departing from the scope of the present disclosure. For example,a radially outwardly extending member may be fixed to DPF 20 and areceptacle, recess or slot may be formed in first bracket assembly 72.

When first band clamp 40 and second band clamp 42 are tightened, anouter surface 109 of poka-yoke ring 100 is spaced apart a minimaldistance from surface 98 of second blade 96. In similar fashion, aninner circumferential surface 110 of first blade 86 is spaced apart arelatively small distance from outer cylindrical surface 89 of DPF 20.

When used in conjunction with a large diesel engine such as that foundon a locomotive or in a marine application, DPF 20 may weigh over 100pounds. By defining the shape and location of first blade 86 and secondblade 96, poka-yoke system 70 provides a cradle for supporting DPF 20during the processes of installing and removing DPF 20 from system 10.In particular, outer surface 109 of poka-yoke ring 100 will engagesurface 98 of second blade 96 and outer surface 89 of DPF 20 engagescurved inner surface 110 of first blade 86 when first band clamp 40 andsecond band clamp 42 are released. To form a cradle and support DPF 20as described, first bracket assembly 72 and second bracket assembly 74are coupled to first flange 46 and second flange 58 at or near a pointclosest to the ground. Gravity will urge DPF 20 into contact with firstblade 86 and second blade 96. Once first band clamp 40 and second bandclamp 42 have been removed or axially displaced to a location clear ofDPF 20, the DPF may be removed by radially translating the DPF in adirection opposite first blade 86 and second blade 96.

The reverse order of operations may be followed to install a cleanedDPF. For example, DPF 20 is oriented to position first end 52 at anupstream location. DPF 20 is lowered into contact with surface 110 offirst blade 86 and surface 98 of second blade 96. DPF 20 is rotateduntil first blade 86 is aligned with slot 90. First band clamp 40 andsecond band clamp 42 are tightened. During the tightening process, outersurface 89 of DPF 20 disengages first blade 86 and second blade 96 tobecome coaxially aligned with DOC 18 and SCR 22.

FIGS. 5 and 6 depict an alternate poka-yoke system identified atreference numeral 200. Poka-yoke system 200 includes a first band clamp202 interconnecting a DOC 204 and a DPF 206. A second band clamp 208couples DPF 206 with an SCR 210. DOC 204 includes a first upstream end212 and a second downstream end 214. DPF 206 includes a first upstreamend 216 and a second downstream end 218. SCR 210 includes a firstupstream end 220 and a second downstream end 222.

Poka-yoke system 200 assures proper upstream and downstream endorientation of DPF 206 by configuring first band clamp 202 to include astepped inner diameter. More particularly, an upstream end of first bandclamp 202 includes a first inner cylindrical surface 226. A downstreamportion of first band clamp 202 includes an inner cylindrical surface228 having a greater diameter than cylindrical surface 226. Similarly,second band clamp 208 includes an inner cylindrical surface 232positioned at an upstream end defining a diameter. A larger innerdiameter is defined by an inner cylindrical surface 234. Cylindricalsurface 234 is positioned downstream from cylindrical surface 232.

DPF 206 includes a stepped outer diameter. A first upstream portion ofDPF 206 includes an outer cylindrical surface 240. A downstream reduceddiameter portion is defined by outer cylindrical surface 242. FIG. 5depicts a properly oriented DPF 206 coupled to DOC 204 by first bandclamp 202. DOC 204 includes an outer cylindrical surface 246 having asmaller outer diameter than outer surface 240 of DPF 206. Outer surface246 is sized to closely mate with inner surface 226 of first band clamp202. Outer surface 240 of DPF 206 is sized to cooperate with innercylindrical surface 228 of first band clamp 202. In similar fashion, SCR210 includes an outer cylindrical surface 248 having an outer diameterlarger than cylindrical surface 242 of DPF 206. Outer cylindricalsurface 248 is sized to cooperate with inner cylindrical surface 234 ofsecond band clamp 208. Reduced diameter outer cylindrical surface 242cooperates with reduced diameter inner cylindrical surface 232 of secondband clamp.

FIG. 6 represents an interference condition that would exist if anoperator attempted to install DPF 206 in reverse with downstream end 218positioned upstream of upstream end 216. An interference condition wouldexist between outer cylindrical surface 240 and inner cylindricalsurface 232. Furthermore, inner cylindrical surface 228 of first bandclamp 202 would not engage reduced diameter outer cylindrical surface242 of DPF 206. As such, poka-yoke system 200 assures proper orientationof DPF 206.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. An exhaust treatment system including first andsecond spaced apart portions in receipt of exhaust emitted from aninternal combustion engine, the exhaust treatment system comprising: anexhaust treatment device including a housing having a first outerdiameter at an open first end of the exhaust treatment device, thehousing having a second outer diameter different than the first outerdiameter at an open second end of the exhaust treatment device; a firstclamp adapted to couple the exhaust treatment device to the firstportion, the first clamp including a stepped inner diameter having firstand second surfaces having different diameters such that the firstsurface of the first clamp engages the first portion and the secondsurface of the first clamp engages the exhaust treatment device when thefirst end of the exhaust treatment device is positioned adjacent to thefirst portion; and a second clamp coupling the exhaust treatment deviceto the second portion, wherein the second end of the exhaust treatmentdevice is configured to interfere with the first clamp to precludecoupling the first portion to the exhaust treatment device when thesecond end of the exhaust treatment device is positioned adjacent to thefirst portion.
 2. The system of claim 1, wherein the first clampincludes a band clamp.
 3. The system of claim 1, wherein the exhausttreatment device includes a diesel particulate filter.
 4. The system ofclaim 1, wherein the second clamp also includes a stepped innerdiameter.
 5. The system of claim 4, wherein the stepped inner diameterof the first clamp is the same size as the stepped inner diameter of thesecond clamp.
 6. The system of claim 1, wherein the stepped innerdiameter of the first clamp includes a first inner cylindrical surfacehaving a first size and a second inner cylindrical surface having asecond size greater than the first size.
 7. The system of claim 6,wherein the first size of the first inner cylindrical surface is lessthan the second outer diameter of the housing.
 8. The system of claim 1,wherein the exhaust treatment device housing includes a stepped outerdiameter.
 9. The system of claim 8, wherein the housing includes a firstcylindrical surface having the first outer diameter at the first end ofthe exhaust treatment device and a second cylindrical surface having thesecond outer diameter at the second end of the exhaust treatment device.10. The system of claim 9, wherein the second outer diameter is greaterthan the first outer diameter.
 11. The system of claim 10, wherein thefirst cylindrical surface of the housing is configured to be spacedapart from the second clamp when the second end of the exhaust treatmentdevice is positioned adjacent to the first portion and the second clampengages the second portion.
 12. An exhaust treatment system comprising:a first exhaust conduit; a second exhaust conduit; an exhaust treatmentdevice positioned between and immediately adjacent to each of the firstand second exhaust conduits, the exhaust treatment device including ahousing having a first outer diameter at an open first end of theexhaust treatment device, the housing having a second outer diameterdifferent than the first outer diameter at an open second end of theexhaust treatment device; and a clamp including an inner surface havinga first portion with a first diameter configured to directly engage thefirst exhaust conduit and a second portion with a second and differentdiameter configured to directly engage the exhaust treatment device whenthe exhaust treatment device is positioned with its first end adjacentto the first exhaust conduit, wherein the inner surface of the clamp isconfigured to be spaced apart from one of the housing and the exhausttreatment device when the second end of the exhaust treatment device isadjacent the first exhaust conduit.
 13. The system of claim 12, whereinthe exhaust treatment device includes a diesel particulate filter. 14.The system of claim 12, wherein the clamp includes a band clamp.
 15. Thesystem of claim 12, wherein the housing includes a first cylindricalsurface having the first outer diameter at the first end of the exhausttreatment device and a second cylindrical surface having the secondouter diameter at the second end of the exhaust treatment device. 16.The system of claim 15, wherein the first outer diameter is greater thanthe second outer diameter.
 17. An exhaust treatment system comprising: afirst exhaust conduit; a second exhaust conduit; an exhaust treatmentdevice positioned between and immediately adjacent to each of the firstand second exhaust conduits, the exhaust treatment device including ahousing having a first outer diameter at an open first end of theexhaust treatment device, the housing having a second outer diameterdifferent than the first outer diameter at an open second end of theexhaust treatment device; and a clamp including an inner surfaceincludes a stepped inner diameter having first and second surfaceshaving different diameters such that the first surface of the clamp isconfigured to engage the first exhaust conduit, the second surface ofthe clamp being configured to engage the exhaust treatment device whenthe exhaust treatment device is positioned with its first end adjacentto the first exhaust conduit, wherein the inner surface of the clamp isconfigured to be spaced apart from one of the housing and the exhausttreatment device when the second end of the exhaust treatment device isadjacent the first exhaust conduit.